Electric circuit interrupter



April 18, 1933. w. E. PAUL 1,904,519-

ELECTRIC CIRCUIT INTERRUPTER Filed Sept. 24, 1931 William E. Paul,

vHis tbo'rheg.

ing side of the piston 21 with the result that the pressure in the valve chamber opens the valve 18 and subjects the insulating liquid in the chamber 20 to the same pressure.

interruption of the circuit is caused by separation ofthe contacts 5 and 6 concurrent with a jet or blast of insulating liquid from the chamber 2O exhausting between the contacts to the outer oil body by reason of the pressure admitted to chamber 20. To this end, contacts 5 and 6 are provided with piston members 29 and 30 respectively, subject to pressure within the chamber 20, and the contacts are mounted so as to separate within a passage 31 exhausting the chamber 20 to the exterior. rlhe pistons 29 and 30 are acted upon by springs 32 and 33 normally biasing the contacts 5 and 6 into engagement. The two sets of contacts 5, 6 and 8 are suitably connected in series, as by a conductor 34 connecting the lead 11 to the contact 5, and conductors 35 connecting the main contact 6 to the pressure generating contact For the purpose of controlling or limiting the arcing pressure generated, contact 7.is provided with a piston 36 mounted within the housing 9 so that one face is subject to arcing pressure whereas the other face is subject only to low pressure through the opening 37. The piston 36 is biased upwardly by a spring 38 whichmay be designed in accordance with the operating pressures desired.

The method of operation maybe described briefly as follows: Loweringjor switch opening movement of the bridging member l causes separation of the contacts 7 and 8 with the result that an initial arc is drawn in the chamber 13. At this point it should be understood that the initial arc may be formed by blowing of a fuse in series with contacts 5 and 6 if this construction is preferred. As is well known, the formation of an electric arc in oil generates pressure at a very rapid rate, the rate of increase inl pressure depending upon the intensity of the current and length ci arc. ln order to prevent the arcing pressure from becoming excessive, possibly causing destruction of the contact housing, the

`.dierential pressure acting on the piston 36 causes the same to move downwardly so that contact 7 `follows contact 8 thereby limiting lengthening of the arc until the contact` 8 moves entirely out of the housing.

- After or at a predetermined time the pilot valve 23 is opened with the result that the pressure in chamber 17 at once opens the valve 18 due to the greater area of piston 21` and high pressure is immediately communicated to interrupting chamber 20. The pistons 29 and 30 are thereupon forced away from each other against the bias of their springs causing separation of the contacts 5 and 6.while at the same time insulating liquid is exhausted at high velocity through the passage 31 and between the contacts extin- `wed e and ishing the arc drawn at these contacts. ince the gas and arc products are formed in the chamber 13 and remain in that region until the valve 18 is ope-ned, it will be apparent that the blast of insulating liquid between the contacts 5 and 6 is subst. ntially unaffected by arc products.

After the blast of insulating liquid between the contacts 5 and 6 has extinguished the arc, the pressure generating arc, being in series therewith, is likewise extinguished so that the ressure within the contact housing is rapidy dissipated. The housings 9 thereupon refill with oil through the various openings so that the apparatus is in readiness for another operation. In the open circuit position the contacts 5 and 6 are again biased into engagement, the current being open through the contacts 7 and 8. The pilot valve 23 may likewise be maintained open so that the space behind the piston 21 is refilled with oil and the valve 18 closed. Closing of the circuit interrupter b upward movement of the bridging mem r 1 causes engagement of the contacts 7 and 8 and releases the pilot valve so that it is moved onto its seat. l

When 4the circuit interrupter must have high current-carrying capacity, so-called primary contacts are employed to shunt the main part of the current around the secondary or arcing contacts. This general arrangement which is well known inthe art is shown in Fig. 2, the movable primary contacts 39 being connected to the extremities of the lift rod. The contacts 39 coact with the stationary primary contacts 40 which are electrically connected to the lead-in conductors 11 in any suitable manner as by the conductors 40. The primary contacts are of the Awell-known linger type and do not require furt er description. The arrangement is such that the primary contacts are separated a predetermined distance before possible interruption of the circuit since otherwise destructive arcing might occur at the primary contacts.

When a bridging circuit including primary contacts is used in connection with my invention, it is possible to reduce the time required to interrupt the circuit by reason of the separately movable pressure generating contacts. For the purpose of keeping the contacts 7 and 8 in engagement until separation of the primary contacts 39 and 40, a resilient connection or wipe between the contact 7 and piston 36 is provided comprising a spring 41 which is located between the piston 36 and a shoulder 42 forming part of the contact 7. In this case the piston 36 is mounted for rela\ tive movement with respect to the Contact 7. When the bridging member 1 descends, the wipe or overtravel at the contacts 7 and 8 permits opening of the primary contacts prior to separation of the arcing contacts so that the entire current is shunted through the arcing contacts. 'Immediately after the primary contacts have separated, the pressure generating arc is formed by separation of the contacts 7 and 8. Since the actual resistance of the arc is quite small, the formation of the pressure generating arc at once does not increase the voltage across the interrupter terminals so that there is little danger of arcing-over' at the separating primary contacts. The arcing pressure may thereupon build up until the primary contacts have separated a predetermined distance, at which time the valve 18 is opened as illustrated and the circuit at the contacts 5 and 6 immediately interrupted by the high velocity oil blast through the interrupting chamber 20. In this manner the interrupting time is reduced to a minimum and arcing at the primary contacts is precluded sincey interruption of the circuit does not occur until the primary contacts are separated a safe distance. The apparatus is. ".shown in Fig. 2 at the moment of circuit interruption, the primary contacts 39 and 40 being a safe distance apart so that the oil blast is eective to interrupt the circuit.

In certain cases it may be desirable to eliminate the valve 18 so that there is direct communication between the interrupting chamber and pressure generating chamber. This arrangement need not involve appreciable change in design of the housing other than possible closer spacing of the chambers.

It should be understood that my invention is not limited to specific details. of construetion and arrangement thereof herein' illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure y by Letters Patent of the United States, is:

1. A circuit` interrupter of the fluid-break type comprising a pair of contacts separable in an arc extinguishing liquid to form a pressure generating break connected in serieswith a pair of independent and separately movab`e current interrupting contacts, and means for directing pressure generated by arcing at said break so as to cause separation of said independent current interrupting contacts and force a blast of insulating liquid between the same extinguishing arcing.

2. A circuit interrupter of the fluid-break type comprising two independent sets of separately movable contacts connected in series immersed in an arc extinguishing liquid, one set of contacts forming an initial pressure generating arc, and means directing said pressure so as to separate the other set of contacts and force a jet of insulating liquid between the saineV extin ishing arcing.

3. -A circuit interrupter of the Huid-break type comprising two independent sets of separately movable contacts 'connected in series immersed in an insulating liquid, one of said set-s' forming an initial pressure generating arc, means directing said pressure so as to cause subsequent separation of the other set of contacts and force a jet of insulating liquid therebetween, and means responsive to said generated pressure limiting the length of said initial arc. l

4. A circuit interrupter of the fluid-break type comprising a plurality of independent sets of separately movable contacts connected in series and immersed in insulating liquid Within separate chambers, one of said sets forming in one chamber a pressure generating arc, means directing said pressure into another chamber causing interruption of arcing at another set of said contacts, and a valve controlling communication between said chambers.

5; A circuit interrupter of the Huid-break type comprising two sets of'contacts connected in series immersed in insulating liquid, one of said sets forming a pressure generating arc, means directing said pressure so as to cause separation of and interruption of arcin at the other set o'fsaid contacts, and a va ve controlling and delaying the application of said pressure.

6. A circuit interrupter of the fluid-break type comprising a pair of main current interrupting contacts connected in series with a pair of independent and separately movable pressure generating contacts, said contacts immersed in an insulating liquid, means directing pressure generated'at said last named contactsso as to cause separation of said main contacts and force a jet of insulating liquid between the same, a valve-controlling application of said pressure to said main conv tacts, and means controlling actuation of said valve in accordance with circuit opening movement. n

7. A circuit interrupter of the Huid-break type comprising means forming a pressure generating break in an insulating liquid, cir-.

break type including primary current carrying contacts, arc extinguishing means comprising circuit interrupting meansand contacts forming a pressure generating arc immediately after separation of said primary contacts, said pressure tending to cause a blast of insulating liquid across the arc.

formed at said circuit interrupting means, and a valve releasing said pressure to cause interruption of the circuit only when said primary contacts are separated by a distance precluding arcing.

`9. A circuit interrupter of the fluid-break type including pressure generating means within an insulating .liquid and coacting contants between which insulating liquid is forced by said pressure interrupting the circuit, means controlling application of said pressure comprising a valve actuated by said pressure, and a pilot valve reducing the pressure on one` side of said valve causing opening thereof.

10. A circuit interrupter of the Huidbreak type comprising contact housing structure immersed in an insulating liquid, relatively movable contacts formin a pressure generating arc Within a cham er in said housing, said pressure tending to force insulating liquid through a second chamber and between coacting contacts therein to interrupt the circuit, a valve mounted Within said housing controlling communication between said chambers, a pilot valve controlling the opening of said valve by said arcing pressure, and cam structure related to said movable contact opening said pilot valve after predetermined circuit opening movement.

In witness whereof, I have hereunto set my hand.

WILLIAM E. PAUL. 

